Representations of Atheism

[Rev. Rye]

I haven't read Hitchhiker's Guide to the Galaxy, how would you say it deals with the subject of atheism/religion?

Well, just read it. What with it being available in one volume, it's certainly much easier to get into in Discworld.
At any rate, one particularly overt scene includes a digression by the Guide about how the existence of the Babelfish is a proof of the nonexistence of God, precisely because it is so useful and overt that it couldn't be the handiwork of somebody who works in mysterious ways or is supposed to be all-knowing.